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Dry Days To Continue Over South India

The current phase of subdued rainfall is likely to continue over Tamil Nadu, Kerala and Karnataka. Isolated light to moderate showers would occur over Karnataka coast with sporadic rainfall across the Malabar coast. One or two weak thundershowers could develop over Tamil Nadu in the evening with no significant rainfall. This pattern is likely to continue until a wet phase arrives around September 2nd.

The current low pressure area near Jharkhand is likely to trigger scattered showers with isolated heavy rainfalls across East and East Central India which includes Odisha, eastern Andhra Pradesh, Madhya Pradesh, Jharkhand and isolated parts of Bihar, West Bengal and Telangana. The heaviest rainfall from this spell could be witnessed at Chhattisgarh. Isolated showers will be experienced over the Northern Plains.

Ayodhya in UP for 2nd day records heavy rainfall of 123 mm. Kondagaon in Chattisgarh records 178 mm, while Salekasa in Vidarbha records 138 mm
Chennai: A hot day with temperatures hitting 37 C is likely. Not much on the rain front.

Coimbatore: A warm day peaking at about 32-33 C with little chance of rain.

Madurai: A blazing day in store. Don’t be surprised if the thermometer flares up to 38-39 C. Chances of rain are low here as well.

Fresh Oceanic tropical convergence zone (OTCZ) was ignited by MJO+ER+KW+MRG. First time all equatorial waves are in action at IO to ignite much needed OTCZ. I never seen this type of active waves working all at same time in IO. One more interesting point is that new MISO-cell along ITCZ gets ignited over south-china sea, which will travel in W/NW direction to enter BOB. In combination of these dynamics, rainfall quantum over west-coast, peninsular and central India will increase many folds starting from September 1st week.

Special VS-TS rainfall alert for core-Chennai:
During this period Core-Chennai may witness violent VS-TS (in the order of august 4th, 2015 strength) more than once starting from September 1st week onwards. Good quantum of rainfall might be recorded at many places over Chennai.

that BOB-LPA weakened without significant attaining in strength. Moreover that LPA doesn’t exhibited typical monsoonal LPA’s SW-tilt, which has the ability to ignite good VS-TS along its SW-periphery including strengthening of off-shore trough along west-coast. so rainfall chances over Chennai diminished unexpectedly.

But very good VS-TS days (more than a single day) are ahead for Core-Chennai starting from September 1st week.

this time no chance of weakening (whether monsoonal LPA forms over BOB/over land) as already good convection around OTCZ developed by these waves unlike last 2 times. Moreover very nice MISO-cell get ignited along ITCZ and will enter BOB without any big hurdle. Most importantly west-pacific is inactive.

in simple words we can assume this scenario as SWM-onset type phenomenon that takes place along Kerala & KTK coasts, which will trigger a monsoonal LPA along SWM-axis (perfect example for this type is June 3rd week wide-spread RF event that occurred in 2015, but might happen in less intensity to that).

Why does everyone associate the success/failure of one month’s rainfall with Nungambakkam alone ? Nungambakkam was excess and the wettest IMD station in July in Chennai region. But it was a failure for entire TN.

August has been normal for TN on whole and good for South Chennai and very good for northern suburbs for Chennai as well. Just because Nunga missed out doesn’t mean it was a failure..

OMG.. ECMWF latest update indicates a UAC passing through GOM and adjoining S TN near Kanyakumari.. Thankfully it’s forecast to only be well marked at the 500 hPa level, meaning it will not influence thunderstorm movement over N TN that much.

According to the current situation and conditions, here is the general model conditions. This is NOT my personal view, just what the models indicate! I stick to my word that intense storms start on Sept 2nd and continue for a few days.

Model consensus will change slightly, but it is good that all models are agreeing to these events.

September 2nd – Increase in rainfall with isolated/scattered thunderstorms returning to TN, especially C TN and S TN
September 3rd – Heavy thunderstorms all across Tamil Nadu. Intense storms to sweep across N TN including coastal area in the night.
September 4th – Widespread storms across TN yet again, this time parts of SI Karnataka expected to receive heavy rains. Heavy storms in the night for many areas C TN and parts of N, S TN
September 5th – Severe thunderstorms all across TN, SI KTK and Rayalaseema. VERY VERY HEAVY storms expected for N TN and S AP in the night.
September 6th – Storms to continue